Power is a common theme. Cersei is all about power, and when an OC is introduced, the power dynamic becomes a central focus. Whether the OC is trying to gain power through Cersei or is a threat to her power, it drives the story. Another theme is loyalty. Cersei values loyalty, but also has a hard time trusting. So, the OC's loyalty or lack thereof can create a lot of tension. Love can also be a theme, though it might be a twisted form of love, given Cersei's nature.
Revenge is another theme. Given the many slights and betrayals Cersei experiences in the original story, fanfictions sometimes focus on her seeking revenge. It could be revenge against her enemies in King's Landing or those who have wronged her family in the past.
One common theme is the struggle for power. Even while pregnant, Cersei is a character who desires power. So many fanfictions explore how she tries to maintain or gain more power during her pregnancy. Another theme could be family. Her pregnancy might change her relationships with her family members, and this is often explored in these stories.
One common theme is the struggle for power within the Lannister family dynamic. Since Cersei is so power - hungry, her OC daughter might also be drawn into the power games of King's Landing. Another theme could be the idea of identity. Growing up as a Lannister has its own set of expectations, and the OC daughter may have to figure out who she really is outside of her family's reputation. Also, themes of love and betrayal often come up. She might face situations where she has to choose between loyalty to her family and her own feelings.
Power is a common theme. Since the Lannisters are known for their thirst for power, many 'oc lannister fanfiction' stories revolve around how an oc deals with power within the family. Another theme is loyalty, whether it's the oc's loyalty to the Lannister family or the loyalty of the family members to each other.
One common theme is the idea of enemies - to - lovers. Given their opposing positions in the original story, it's interesting to see how fanfic writers transform their relationship. Another theme could be political intrigue. Since both are involved in the power games of Westeros, fanfictions often explore how their relationship affects the political landscape.
You can start by looking on Archive of Our Own (AO3). It has a large collection of fanfictions, and there are likely many Cersei Lannister OC ones there. Just use the search function and type in relevant keywords.
In Cersei Lannister x OC fanfiction, the character dynamics can be very interesting. Cersei is a complex character with her own motives and desires. When paired with an Original Character (OC), it allows for new storylines. For example, the OC could be someone who challenges Cersei's power-hungry nature or perhaps becomes an unexpected ally. Their interactions might lead to power struggles, emotional turmoil, or even a strange sort of friendship. The key is how the author develops their relationship in the context of the 'Game of Thrones' universe.
There's also 'Cersei and the Unknown Heir'. In this fanfiction, the OC is a supposed heir to a powerful house and how Cersei deals with this threat and possible alliance is the focus. It's full of political intrigue which is typical of Cersei's storylines.
To develop the male OC, start with his goals. Maybe he wants to gain power and sees Cersei as a means to that end. His appearance can also play a role. If he has a striking look, it might attract Cersei's attention. His relationships with other characters are crucial too. If he has a close friend or mentor, they could influence his actions towards Cersei. For instance, if his mentor warns him about Cersei's dangerous nature, he has to decide whether to listen or pursue his own desires.
Love and friendship are also common themes. The oc might form a deep emotional bond with Jaime, whether it's romantic love or a strong friendship. This bond can help Jaime grow as a person. In some fanfictions, their relationship is what gives Jaime the strength to face his demons. Another theme could be power dynamics. Jaime comes from a powerful family, and the oc's relationship with him can either disrupt or reinforce those power structures.